Transcript HIGH-POWER TARGETS R&D FOR LBNE: STATUS AND FUTURE PLANS P. Hurh FNAL 5/2/11

HIGH-POWER TARGETS R&D FOR LBNE:
STATUS AND FUTURE PLANS
P. Hurh FNAL
5/2/11
Neutrino beam to DUSEL, South Dakota
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
THE NEUTRINO BEAM FACILITY AT FERMILAB
Start with a 700 kW beam. Upgradeable to > 2.0 MW.
 Allow NUMI/MINERVA/NOvA
running with LBNE
 Maximize distance between
target and Near Detector
~400 ft underground
250 meters long
48 degree hor. bend
to point to SD
~150 ft underground
~250 ft underground
LBNE Primary Beam ~ 1/6 of Main Injector
Primary beam energy (protons from the Main Injector) from 60 to 120 GeV
Overview
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LBNE 2.3 MW Default design
LBNE Target R&D
 Graphite
irradiation tests
 Beryllium target analysis
 Beryllium survival in high intensity beam
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
LBNE “default” target design
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Based on 2005 IHEP study
Graphite cylindrical segments pre-loaded in
stainless steel sheath with annular water cooling
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
LBNE “default” target design issues
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Hydraulic thermal shock in water (“water hammer”)
Off-center beam (accident conditions)
Beam windows
Graphite radiation damage
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
LBNE Graphite R&D
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Why Graphite?
 Excellent
for thermal shock effects (lower CTE, very low
E, high strength at high temperatures)
 Not toxic (no mixed waste created)
 Readily available (inexpensively) in many grades and
forms

Why not Graphite?
 Rapid
oxidation at high temperatures
 Radiation damage
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Graphite R&D: Radiation Damage
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Rapid degradation of properties at
relatively low levels of DPA
Evidence of complete structural
failure at 1e21 p/cm2 (BLIP test)
N. Maruyama and M. Harayama, “Neutron
irradiation effect on … graphite materials,” Journal
of Nuclear Materials, 195, 44-50 (1992)
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Graphite R&D:
Irradiation Testing at BLIP
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Tensile samples have gauge width
of 3 mm and thickness of 1 mm
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Working with N. Simos and H. Kirk at
BNL to test samples irradiated by 181
MeV proton beam at BLIP
Testing for:
 Tensile properties (YS, UTS, …)
 Coef. of thermal expansion
 Conductivity
Most samples encapsulated in argon
filled, stainless steel capsules to isolate
from water cooling bath
About 150 samples in total
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Graphite R&D:
Irradiation Testing at BLIP
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Material
#
Tensile
#
CTE
K
Motivation
C-C Comp (3D)
10
8
?
First BLIP test showed massive failure
POCO ZXF-5Q
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6
.46
NuMI/NOvA target material
Toyo-Tanso IG 430
42
6
.51
“Nuclear Grade” used for T2K
Carbone-Lorraine 2020
21
6
.60
CNGS target material
SGL R7650
21
6
.66
NuMI/NOvA Baffle material
Saint-Gobain AX05 hBN
0
6
.80
Highest K wild card (low flex strength)

K Factor is a thermal shock resistance parameter used by Luca Bruno
to evaluate candidate materials for targets/windows
 K=(UTS*Cp)/(E*CTE)
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Graphite R&D:
Irradiation Testing at BLIP
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Irradiation run complete
Currently in testing phase
Preliminary results on CTE changes
now available
Tensile tests starting (2 weeks ago)
181 MeV proton beam
Peak integrated flux about
5.9e20 proton/cm2
Corresponds to 0.14 DPA
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Graphite R&D:
Irradiation Testing at BLIP
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Water immersed c-c samples
showed structural damage (as
before).
Argon encapsulated c-c and
graphite samples showed little
damage (not pictured here)
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Graphite R&D:
Irradiation Testing at BLIP
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Graphite R&D:
Irradiation Testing at BLIP
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Graphite R&D:
Irradiation Testing at BLIP
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CTE of almost all graphite samples reduced after
irradiation (0.07-0.14 DPA) on first thermal cycle to
300 ˚C depending on graphite type
After first cycle CTE is increased to about 10% more
than un-irradiated samples, regardless of graphite type
Neutron irradiation studies on graphite consistent with
10% rise in CTE (closure of Mrozowski cracks) and
inconsistent with “annealing” at 300 ˚C (significant
annealing only above 1000 ˚C)
Behavior might be explained by gas production or
other mechanism associated with high energy proton
irradiation (or lower irradiation temperatures)?
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Graphite R&D: Irradiation Testing at BLIP
Preliminary Tensile Test Results
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Graphite R&D: Irradiation Testing at BLIP
Preliminary Tensile Test Results
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Graphite R&D: Irradiation Testing at BLIP
Preliminary Tensile Test Results
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Beryllium R&D:
Conceptual Design Studies at STFC-RAL
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High Power Target Group:
CJ Densham
O Caretta
TR Davenne
MD Fitton
P Loveridge
M Rooney
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Graphite radiation damage issues
prompted LBNE to look at Beryllium as
an alternative target material for 2+
MW proton beam power
Accord with (STFC) RAL’s Target
Engineering Group
Beryllium target simulations at 2+ MW
 Integrated Be target and horn
conceptual design
 Cooling technology R&D (gas, water,
water spray)
 Proton beam window conceptual design
 Air cooled Be target for 700 kW

Focus On:
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Beryllium R&D:
Be Target Simulations
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Analysis encompasses:
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Physics (FLUKA) – Energy Deposition & Figure of Merit
Thermal/Structural (ANSYS)
Dynamic/Stress-wave (Autodyn & ANSYS)
Off-center beam cases
Beam Parameters:
Pulse Length = 9.78 micro-sec
Proton Beam
Energy (GeV)
Protons per
Pulse
Repetition
Period (sec)
Proton Beam
Power (MW)
Beam sigma,
radius (mm)
120
4.9e13
1.33
0.7
1.5-3.5
60
5.6e13
0.76
0.7
1.5-3.5
120
1.6e14
1.33
2.3
1.5-3.5
60
1.6e14
.76
2
1.5-3.5
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Beryllium R&D:
Be Target Simulations: Structural
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Representative
plot of
equivalent
stress
End of Pulse
120 GeV, 0.7
MW beam
9mm radius Be
Sy~270 MPa
at 150 C
Beryllium R&D:
Be Target Simulations: Structural (non-dynamic)
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Stresses probably too high for 2 MW cases with 1.5 mm beam sigma
radius, but well within reason for 3.5 mm beam sigma radius
Room for optimization (in length as well)!
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Beryllium R&D:
Be Target Simulations: Dynamic
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2.3 MW
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120 GeV
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
3.5 mm
sigma spot
Compare to
88 Mpa for
static case
(double)
Mainly
longitudinal
stresswaves
Beryllium R&D:
Be Target Simulations: Dynamic
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2.3 MW
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120 GeV
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3.5 mm sigma spot
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50 mm Segments
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Peak eqv stress
reduced to 109
MPa from 173 MPa
Beryllium R&D:
Be Target Simulations: Off Center Beam
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2.3 MW
120 GeV
3.5 mm sigma spot
2 sigma offset
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Clearance to Horn Inner Conductor is ~5mm
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Bending stress and resonance is a problem
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Target will need radial supports
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Beryllium R&D:
Be Target Simulations: Spherical
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Beryllium R&D:
Be Target Simulations: Spherical
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Spherical shape advantages
Eliminates stress concentrations

Reduces dynamic stress
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Allows pions to escape
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Allows cooling in target central area
Peak stress with off centre beam
800
Figure of Merit as a function of target diameter
(1 m long cylinders; sigma=r/3)
160
140
120
100
80
rod
60
spheres
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20
Peak Von-mises stress as a result of 2sigma off centre beam [MPa]

Figure of Merit [pions(+/-)/primary *GeV 2.5]
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0.7MW spheres
700
2.3 Mw spheres
0.7 MW cylinder
600
2.3 MW cylinder
nominal yield strength and
endurance limit for beryllium
Max design stress (as specified
by Fermilab)
500
400
300
200
100
0
0
5
10
15
Target diameter [mm]
20
25
5
10
15
20
Diameter of cylinder or sphere [mm]
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
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Beryllium R&D:
Be Target Simulations: FoM
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Figure of Merit

Provide simple, faster way to gauge effects of target/beam parameter
changes on yield of neutrinos of interest

Proposed by R. Zwaska
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Beryllium R&D:
Failure Criteria – Simulation versus Reality
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Predicted Peak Energy Deposition for LBNE 2.3
MW with 1.5 mm beam sigma radius was 846 J/cc
and thought to cause stresses too high for Be to
survive
But P-bar Target (FNAL) has a Beryllium cover that
regularly sees 1000 J/cc and shows no evidence of
damage
ANSYS analysis for similar conditions suggests peak
equivalent stresses of 300 Mpa (elastic-plastic,
temp-dependent mat’l properties, but not dynamic)
Dynamic stresses could be 30-50% higher
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Beryllium R&D:
Failure Criteria – Simulation versus Reality
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120 GeV
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0.2 mm sigma
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Elastic/plastic
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Temp Dependent
Mat’l Properties
Peak Seqv is 300
MPa
Peak Temp is
~800 C
Be Melting Temp
is 1278 C
Be UTS at 600 C
is ~150 MPa
Beryllium R&D:
Failure Criteria – Simulation versus Reality
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Rotated 17 degrees every pulse
Moved 1 mm vertically every 2e17
protons
Typical beam sigma was 0.195 mm
(last 1-2 months of running at 0.15
mm)
Typical ppp was 8E12
This target saw about 5e6 pulses
at the time photo was taken
Pbar Target 7 without Be cover.
Inconel Target Material is
Consumable!
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Beryllium R&D:
Failure Criteria – Simulation versus Reality
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Possible explanations
 Small
areas of deformation not visible
 Analysis
indicates about 0.05 mm of plastic deformation on
surface in an outward “bump” with diameter of about 1 mm
 Beam
profile is not gaussian
 At
such small sigma, peak energy deposition would be
reduced greatly if profile were flat in center of beam
 Fast
energy deposition rate creates high strain rates
 Yield
strength of metals increases for high strain rates
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Beryllium R&D:
Failure Criteria – Simulation versus Reality
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Max strain predicted
is 0.01 strain
Pulse length is 1.6
micro-sec
Strain rate is over
6,000 s-1
For LBNE 2.3 MW, 3.5
mm sigma, strain
rate=100 s-1
For LBNE 2.3 MW, 1.5
mm sigma, strain
rate=340 s-1
Beryllium R&D:
Failure Criteria – Simulation versus Reality
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T Nicholas, et al., Mechanical
Properties of Structural Grades
of Beryllium at High Strain
Rates, AFML-TR-76-168, Air
Force Materials Laboratory,
Wright Patterson Air Force
Base, Ohio, 1976
S200E Be
F.L. Schierloh and S.G Babcock, Tensile
Properties of Beryllium at High Strain Rates and
Temperatures, AFML-TR-69-273, General Motors
Tech Center, 1969
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UTS vs strain rate
Yield and Ultimate Stresses increase by 2540% at strain rates greater than 100 s-1
Significant increased hardening as well
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Beryllium R&D:
Failure Criteria – Simulation versus Reality
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Just DS of Target
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Higher Temperature
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P. Hurh: High-Power Targets R&D for LBNE
Damage seen on Be
Lithium Lens Windows
5/2/11
Higher Stress (10,000
psi of Li pressure on
other side)
Damage observed
after 8 months of
running at reduced
spot size of 0.15 mm
sigma and not at
larger spot size (0.19
mm sigma)
Beryllium R&D:
Failure Criteria – Simulation versus Reality
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
More work needs to be done in this area to set
limits of Be in high power proton beams
 Effects
of irradiation and temperature
 Refined simulation of actual conditions
 In beam validation/benchmarking test

For now, set conservative limits and push the
envelope later…
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Summary
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Although challenging, critical design issues have
been identified for high power, solid targets
Graphite radiation damage testing at BNL
First stage Be target design study by RAL shows
promise of Be target for LBNE at 2.3 MW
Future work includes:
 Continuation
of graphite sample testing
 Further Be design studies
 Be target testing at P-bar source OR new High RadMat
Facility (CERN)?
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Thanks to all
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
N. Simos, J. Misek, H. Kirk, J. O’Conor, C. Densham,
T. Davenne, P. Loveridge, M. Fitton, M. Rooney, O.
Caretta, J. Hylen, R. Campos, N. Mokhov, T.
Grumstrup, R. Zwaska, V. Sidorov, A. Leveling and
many others…
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Additional slides, if time…
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Thermal Shock
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Ta-rod after irradiation with 6E18 protons in 2.4 s
pulses of 3E13 at ISOLDE (photo courtesy of J. Lettry)
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Simulation of stress wave propagation in Li lens
(pbar source, Fermilab)
Fast expansion of material surrounded by cooler material
creates a sudden local area of compressive stress
Stress waves (not shock waves) move through the target
Plastic deformation or cracking can occur
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Thermal Shock
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Methods to overcome thermal shock:
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Material Selection
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High specific heat
Low coefficient of thermal expansion
Low modulus of elasticity
High strength (tensile and fatigue) at elevated temperature
Segment target length
Avoid stress concentration prone target shapes
Pre-load in compression
Manipulate beam parameters (spot size, intensity)
Must design for accident conditions
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Maximum intensity and smallest spot size
Mis-steered beam on target
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Heat Removal
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25-30 kW total energy deposited (2.3 MW proton
beam)
Easy to remove with water
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Tritium production
Hydrogen gas production
Thermal shock in water
(Water Hammer)
150 atm IHEP report (actual
pressure rise will be much
less due to flexibility of
pipe)
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Heat Removal
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Methods of avoiding “water hammer”
2 Phase cooling (bubbles)
 2 Phase cooling (heat pipe)
 Spray cooling (NuMI horn)
 Gas cooling
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T2K 750 kW graphite target, Helium cooling
 Mini-BooNE beryllium target, Air cooling

P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Radiation Damage
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Displacements in metal
crystal lattice
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Embrittlement
Creep
Swelling
Damage to
organics/plastics
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Cross-linking (stiffens,
increase properties)
Scission (disintegrate,
decrease properties)
Molecular Damage Simulations of peak damage
state in iron cascades at 100K.
R. E. Stoller, ORNL.
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Radiation Damage
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Tungsten cylinders
irradiated with 800
MeV protons and
compressed to 20%
strain at RT.
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A) Before irradiation
B) After 3.2 dpa
C) After 14.9 dpa
D) After 23.3 dpa
Data exists for neutron
irradiation, less for
proton irradiation

Gas production much
higher for high energy
particle irradiation
S. A. Malloy, et al., Journal of Nuclear Material,
2005. (LANSCE irradiations)
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Oxidation
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Oxidation reaction is very fast for carbon at high temperatures
Need sealed target jacket with beam windows and pump/purge system
Beryllium avoids this?
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Lance Snead and Tim Burchell
Oak R idge National Laboratory
Radiation Accelerated Corrosion
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Al 6061 samples
displayed significant
localized corrosion
after 3,600 Mrad
exposure
NuMI target chase air
handling condensate
with pH of 2
NuMI decay pipe
window concerns
R.L. Sindelar, et al., Materials
Characterization 43:147-157
(1999).
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Radiation Accelerated Corrosion
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Photograph of NuMI decay pipe US window showing corroded
spot corresponding to beam spot
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Radiation Accelerated Corrosion
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MiniBooNE 25 m
absorber HS steel
failure
(hydrogen embrittlement
from accelerated
corrosion).
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Survivability is relative
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P-bar consumable target
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Ran in consumable mode
for 2 plus years
Change-out time 12 hours
maximum
Over-heating, oxidation,
thermal shock led to
damage
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
New P-bar Target
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~2e19 integrated
protons on target
Courtesy of
Ron LeBeau, Tony
Leveling, & Ryan
Schultz
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Thermal Shock
52

Work at RAL-Sheffield by R. Bennett and G.
Skoro to study solid targets for NuFact
 Pulsed
Ta & W wire testing
 Benchmark simulation techniques
 Show promise of solid W at 4 MW

Upcoming Publications:
 G.P.
Skoro et al. / Journal of Nuclear Materials
409 (2011) 40–46
 Nuclear Inst. and Methods in Physics Research A,
DOI:10.1016/j.nima.2011.03.036
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Introduction
Current pulse – wire tests at RAL
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Tantalum wire – weak
at high temperatures
Tungsten – much better!!!
The Finite Element Simulations have been used to
calculate equivalent beam power in a real target and to
extract the corresponding lifetime.
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Yield strength of tungsten – our results
Combination of visual observation of the wire and LS-DYNA simulations
Stress in
NF target
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P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Thermal Shock
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SNS Hg Target
Cavitation problems
J. Haines, B. Riemer, ORNL
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Physics Optimization
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Physics Simulation
(Full optics or reduced set,
Figure of Merit)
Target Design
Energy Deposition
Simulation
Iterative process makes it difficult to isolate the design efforts
Figure of Merit helps to reduce simulation requirements
Leads to novel target ideas (multiple materials, spherical targets)
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Residual Radiation
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Measured dose rates for NuMI
Horn 1 water line repair (250
kW proton beam)
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Dose rates for 2.3 MW beam components estimated at 300-800 Rad/hr
Systems for component change-out and repair must be developed (IE Remote
Handling)
Operations activities must be integrated into the conceptual design of target
components
P. Hurh: High-Power Targets R&D for LBNE
5/2/11
Residual Radiation
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LBNE Remote Handling Equipment (courtesy of V. Graves and A. Carroll, ORNL)
P. Hurh: High-Power Targets R&D for LBNE
5/2/11